The USA was the closest rival to Germany for the variety of slide adders made. However it was unsurpassed in the field of dial adders in the twentieth century. Eventually its calculator industry succumbed to Japanese imports (such as the Magic Brain) before mechanical calculators disappeared under the onslaught of electronics.

“Tom Thumb Adding Machine”, Western Stamping Co, Jackson, Michigan8 slides, 9 digit display5.5 x 3.3 inchesSteel & plasticWith red/clear vinyl wallet, metal stylus with plastic ends, and instructions1950sThis is identical to the later type of Baby Calculator, seen above, except for the printing on the face plate and the type of case.

Consul the Educated Monkey (Reproduction)The original was patented in the USA in 1916. Moving Consul’s feet to point to two numbers results in the answer being shown in the window between his hands. The original was supplied with cards which also enabled addition, subtraction and division to be carried out but the reproduction is not. The original was made in the USA - the reproduction does not say where it was made - it came in a cream coloured card box with transparent section in the lid.Buyer Beware - I bought mine on EBay; it was listed under Antiques - Scientific Instruments and, although the seller gave the condition as new he did not state that it was a reproduction. Fortunately I had only paid a little more than its actual worth.

“Addometer”Reliable Typewriter & Adding Machine Co, Chicago, andTaylor’s, 74 Chancery Lane, London (who milled out the Reliable company’s name and address and stamped their own in its place)8 dials, 8 digit displaySteel; 11.5 x 2.3 inchesWith stylus and case “Manufactured in England”Sterling currency version; red dials for shillings and last two dials for pence and halfpennies/farthings respectively.Mid 20th century